Some good points Tayln made. I was specifically referring to what twist you could get in the barrel (.223 Wylde) which as we know, you can get it in, be it .223 or .556. A couple good articles on the Wylde chamber. If one was looking to put an AR together it would be worth a look to go with the Wylde chamber.
Is a 223 Wylde chamber the best chamber for your AR-15?
www.shootingillustrated.com
It's growing quickly in some shooting circles but what is 223 Wylde and why should you consider a rifle chambered in it instead of 5.56 or .223 Remington?
www.ammunitiontogo.com